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Coal processing plant which breaks coal into various sizes

A coal breaker is a coal processing plant which breaks coal into various useful sizes. Coal breakers also remove impurities from the coal (typically slate) and deposit them into a culm dump. The coal breaker is a forerunner of the modern coal preparation plant. Coal tipples typically were used at bituminous coal mines, where removing impurities was important but sorting by size was only a secondary, minor concern. At least one source claims that, in 1873, coal breaking plants were found only at anthracite mines in Pennsylvania.

The first function of a coal breaker is to break coal into pieces and sort these pieces into categories of nearly uniform size, a process known as breaking. The second function of a coal breaker is to remove impurities (such as slate or rock), and then grade the coal on the basis of the percent of impurities remaining. Prior to entering the breaker, the coal would be crushed and sorted in a coal tipple Passing the coal through the tipple was an essential pre treatment process for coal washing, however, because the impure coal must be of similar sized lumps for coal washing to work. Smaller lumps of coal were considered nonmarketable and left in the mine. Shortly after the start of the 19th century, experiments in the United States showed that if anthracite coal lumps were more uniform in size and air flowed more evenly around the fuel, anthracite would burn hotter, more cleanly, and for a longer period of time than bituminous coal. Jesse Fell was the first to successfully burn anthracite coal on an open air grate. His method and 'discovery' in Wilkes Barre, PA in 1808 led to the widespread use of coal as the fuel source that helped to foster America's industrial revolution. Anthracite coal began to be widely used in Wales in 1813 and France by 1814, and throughout the eastern United States by 1828. Efforts were soon made to discover ways to process anthracite coal to achieve the desired uniformity. The modern coal breaker can be traced to 1844. The first steam powered shaking screens were used in the U. S. 1890, and the first steam powered coal washers installed in 1892. The use of breaker boys began in the U. S. around 1866. The breaker boys would sit on wooden seats, perched over chutes and conveyor belts, picking slate and other impurities out of the coal. Breaker boys worked 10 hours a day for six days a week. The work was hazardous. Breaker boys were forced to work without gloves so that they could handle the slick coal better. Technological innovations in the 1890s and 1900s such as mechanical and water separators designed to remove impurities from coal significantly reduced the need for breaker boys, but adoption of the new technology was slow. The practice of employing children in coal breakers largely ended by 1920 because of the efforts of the National Child Labor Committee, sociologist and photographer Lewis Hine, and the National Consumers League, who educated the public about the practice and succeeded in passing child labor laws. The regulation of coal breakers came slowly in the United States. In the United Kingdom, the government enacted a law in the mid 19th century requiring that coal breakers be built away from mine entrances. But in the U. S., neither the federal government nor the states adopted regulation of coal breakers until after many lives had been lost. Two disasters prompted the adoption of legislation. The first occurred on September 6, 1869, when a small explosion at the Avondale mine in Plymouth, Pennsylvania, blew flames up the mine shaft. No legislative or regulatory action was taken at that time. But in 1871, a fire destroyed the wooden breaker built over a mine opening in West Pittston, Pennsylvania, trapping and killing 24 miners. Despite a shift away from wooden construction of coal breakers and opposition from the coal industry, the state of Pennsylvania adopted a law in 1885 requiring that coal breakers be situated at least 200 feet from the opening of any mine. passed sorted coal of a uniform size over a corrugated iron plate that tended to force the flat slate upright. The upright slate would be caught between horizontal iron bars suspended over the corrugated plate, the bars suspended high enough over the plate to permit coal to pass beneath them. The dense media drops to the bottom of the tank, sending water and the lighter material (such as coal) over the top for collection and drying. As many coal breakers handled heavier loads of coal, wooden buildings were abandoned in favor of structures made entirely of steel or reinforced concrete. were also employed. However, changing demand for coal in the post World War II era led to the abandonment and consolidation of many coal breaking plants. Tipples, coal washing plants, and coal breakers were often merged into a single large plant to achieve economies of scale. Automation led to very significant reductions in the number of people needed to run plants, with smaller modular facilities sometimes requiring only a single operator. These coal preparation plants often accepted coal from several mines, and many were built far away from operating mines. By the 1970s, many coal breakers around the world were being shut down in favor of newer, larger coal preparation plants.

Ideally, coal breakers were placed so that the top of the breaking plant was equal to or slightly below the mine mouth so that gravity would move the coal to the breaking plant. Where this was not possible, coal would be hoisted to the top of the coal breaking plant. A boiler and boilerhouse would be located nearby to provide power for the hoist, moving screens, jigs, and crushers (although in more modern times this is supplied by electricity), along with an engine house (to house the engine for the hoist), pumps and pumphouse (to supply the coal washing machines with water), and headframe (for the hoist). The typical coal breaking plant was often eight or nine stories tall, sometimes rising 150 feet high or more. In the typical coal breaking plant at the beginning of the 20th century, the coal entered the plant at the upper floor and slid down a gently inclined "picker table" where breaker boys removed obvious impurities such as rocks and large pieces of slate and threw them down chutes to the culm pile. The breakers also removed obviously clean lumps of coal and sent them down a separate "clean coal" chute for crushing. Lumps intermixed with impurities would go down a third chute for crushing and further cleaning. On the second level of a typical breaker, coal would be roughly sorted. The fuel would move over sorting bars, with the various sizes of coal going down different chutes. Each type of roughly sorted coal would next pass over a "slate picker screen" (sometimes called a "mud screen"), with the round coal falling through the screen and the flat slate passing over the screen to fall down a chute to the culm pile. Coal passing through the slate picker screen would then be sorted by additional screens. Some of these second screens were composed of flat iron perforated by holes of larger size toward the rear (where the coal entered) and smaller holes toward the front. These flat screens were sometimes shaken back and forth (hence the name "shaking screens"), which not only removed dirt and sulphur from the coal but broke down larger lumps of coal into smaller sizes and sorted it for further cleaning and processing. Other screens were cylindrical, making 10 revolutions per minute and performing the same function as shaking screen. Flat and cylindrical screens could be single jacketed (a single screen) or double jacketed (two screens, the first or inner screen having larger openings while the second screen had smaller ones). The third level from the top was the crushing level. Most coal was still lump coal at this stage, and needed to be crushed in order to create smaller, more marketable product. Here, a series of interlocking, toothed crushers or rollers would break lump coal into progressively smaller sizes. On the fourth level down, the coal was further cleaned of impurities. This was originally done primarily by hand, but hand picking was gradually supplanted after 1910 by improved screens and jigs. Although breaker boys worked at all levels of the coal breaker, most of the removal of impurities by hand occurred on this level. (Some picking did occur on the ground level of the coal breaker, where boys would locate good pieces of coal in the culm and return it to the "clean" coal stream.) Some coal might travel to this level directly from second level, if small enough, as at this level the screens and jigs were only capable of handling egg grade coal and smaller. This area of the coal breaker was also where most dry screens and wet jigs operated. At this level, the use of conveyor belts (with or without paddles or scoops) was necessarily in order to move the smaller grades of coal, with most belts moving at about 33 feet per minute for pea coal and 50 feet per minute for larger grades. Multiple sorting and picking levels might exist in a single coal breaker, depending on the amount of coal to be processed. Coal and culm were received at the ground level. Dry culm was taken away from the coal breaker by conveyor belt or rail car and dumped nearby. Very fine dry culm was sometimes separated from the heavier culm by forced air and blown through tubes to a separate pile. Wet culm was held in settling tanks or behind a coal slurry impoundment dam to allow particulate to settle out of the water. The "clean" coal, emerging from the coal breaker already sorted into its respective sizes, was collected primarily by rail cars and then delivered to market.